Searching for a set of correlated patterns

New algorithms for searching simultaneously for a set of patterns in a text are suggested, for the special case where these patterns are correlated and have a common substring. This is then extended to the case where it could be more profitable to look for more than a single overlap, and a problem related to the generalization of this idea is shown to be NP-complete. Experimental results suggest that for this particular application, the suggested algorithm yields significant improvements over previous methods.